The present invention relates generally to the field of disc drive storage devices, and more particularly, but not by way of limitation, to optimizing write current to minimize encroachment of magnetic tracks and to maximize off-track read capability (OTC).
Modern hard disc drives comprise one or more rigid disks that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is written on each disc in a plurality of concentric tracks by a transducer assembly mounted on an actuator arm. Typically, the transducer assembly is suspended over the disc from the actuator arm in a slider assembly, which includes air bearing surfaces designed to interact with a thin layer of moving air generated by the rotation of the disks. Transducer assemblies are said to xe2x80x9cflyxe2x80x9d over the disc surface as the disc rotates. To access tracks on the disc, the actuator arm moves in an arc across the disc. The physical distance between the nominal centers of two adjacent tracks is referred to as the xe2x80x9ctrack pitchxe2x80x9d. The track pitch and linear track density define the storage capacity of the disc.
A transducer assembly typically includes a read head and a write head. As a write head writes data to the magnetic disc, it creates a track region called a xe2x80x9cwrite trackxe2x80x9d. As a read head reads data from the magnetic disc, it travels along the write track detecting the recorded signal from a region called a xe2x80x9cread trackxe2x80x9d. The write head is wider than the read head, so that the read head generally follows within the bounds of the write track on the magnetic disc. Ideally, the center of the read track coincides with the center of the write track, but various mechanical limitations invariably cause misalignment (or off-tracking) between the read and write tracks.
Furthermore, characteristics such as the size of the write head, the coercivity of the storage media, the media thickness and the head fly height can affect the width of the write track. Moreover, these parameters can vary among magnetic disks and among transducer assemblies. Accordingly, to maintain acceptable operational tolerances, a write track is typically designed to be narrower than the overall track pitch so as not to encroach one write track into an adjacent write track. The difference in width between the write track and the track pitch, however, introduces wasted space within each track. A need exists to reduce this space without introducing an additional source of errors caused by encroaching adjacent tracks.
The present invention provides a method and apparatus for optimizing write current in a track-of-interest on a storage disc of a disc drive system.
In accordance with a preferred embodiment, a method for selecting an optimized write current for a write head to improve read performance from a track-of-interest on a storage disc is provided, including measuring a plurality of error rates associated with a plurality of test write currents. One of the test write currents is chosen based on the error rates to provide the optimized write current, thereby improving the read performance from the track-of-interest.
In accordance with a preferred embodiment, an apparatus for selecting an optimized write current for a write head to improve read performance from a track-of interest on a storage disc is also provided. The apparatus comprises an off-track read capability processor for measuring off-track read capabilities associated with a plurality of test write currents supplied to the write head. An optimized write current storage unit stores an optimized write current value corresponding to the optimized write current and a head value representing the write head. The optimized write current value, which represents the test write current that corresponds to a maximum of the off-track read capabilities, is stored to the optimized write current storage unit by an optimized write current processor. A disk drive system including the apparatus is also provided.
In accordance with a preferred embodiment, a disc drive system for selecting an optimized write current to improve read performance from a track-of-interest on a storage disc is provided. The disk drive system includes a write head for writing data to the track-of-interest on the storage disc and means for selecting the optimized write current.
These and various other features as well as advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.